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Number of n X 3 integer arrays with each element equal to the number of horizontal and antidiagonal neighbors exactly one smaller than itself.
1

%I #8 Jan 09 2019 12:22:12

%S 4,13,64,230,1012,3928,16428,65736,269908,1091720,4454304,18082796,

%T 73622676,299247292,1217498296,4950677020,20137255328,81894658192,

%U 333086633092,1354665687204,5509630157292,22408041160240,91136102570276

%N Number of n X 3 integer arrays with each element equal to the number of horizontal and antidiagonal neighbors exactly one smaller than itself.

%H R. H. Hardin, <a href="/A266096/b266096.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = a(n-1) + 12*a(n-2) + 5*a(n-3) - 12*a(n-4) - 2*a(n-5).

%F Empirical g.f.: x*(4 + 9*x + 3*x^2 - 10*x^3 - 3*x^4) / (1 - x - 12*x^2 - 5*x^3 + 12*x^4 + 2*x^5). - _Colin Barker_, Jan 09 2019

%e Some solutions for n=4:

%e ..0..0..1....0..0..0....0..0..0....1..0..0....1..0..0....0..0..0....1..0..0

%e ..1..1..2....1..2..0....1..2..1....0..2..1....1..1..1....0..2..1....0..0..0

%e ..0..1..1....1..0..0....0..0..0....1..0..1....1..0..0....1..0..0....1..2..1

%e ..1..0..0....0..0..1....0..0..0....1..1..0....0..0..0....0..0..1....0..0..1

%Y Column 3 of A266101.

%K nonn

%O 1,1

%A _R. H. Hardin_, Dec 21 2015